1. Field of the Invention
This invention relates generally to initiators and, more particularly, to design, fabrication and processing of initiators such as described more fully below, such as sometimes herein as “surface mountable” or “surface mounted.”
2. Discussion of Related Art
Initiators find common usage in a variety of applications. One prominent use of initiators is in motor vehicle occupant safety restraint systems.
It is well known to protect a vehicle occupant using a cushion or bag, e.g., an “airbag,” that is inflated or expanded with gas when the vehicle encounters sudden deceleration, such as in a collision. In such systems, the airbag cushion is normally housed in an uninflated and folded condition to minimize space requirements. Upon actuation of the system, the cushion begins being inflated in a matter of no more than a few milliseconds with gas produced or supplied by a device commonly referred to as an “inflator.”
Various types of inflator devices have been disclosed in the art for the inflation of an airbag such as used in inflatable restraint systems.
One type of known inflator device derives inflation gas from a combustible pyrotechnic gas generating material which, upon ignition, generates a quantity of gas sufficient to inflate the airbag. Such inflator devices often include a gas generant material stored within the inflator device housing and an initiator in combination with the housing that actuates the gas generant material. The initiator typically includes a reactive charge in combination with electrical connectors. A signal sent through the electrical connector(s) actuates the reactive charge, which produces reaction products that actuate the gas generant material.
In view of possibly varying operating conditions and, in turn, possibly varying desired performance characteristics, inflatable safety restraint technology has led to the development of what has been termed “adaptive” or “Smart” inflator devices and corresponding inflatable restraint systems. With an adaptive inflator device, output parameters such as one or more of the quantity, supply, and rate of supply of inflation gas, for example, can be selectively and appropriately varied dependent on selected operating conditions such as one or more of ambient temperature, occupant presence, seat belt usage and rate of deceleration of the motor vehicle, for example.
Pyrotechnic inflators typically may have one or more chambers containing gas generant. Adaptive pyrotechnic inflators having gas generant material in two chambers, which are independently ignited via respective initiators or igniters, have been referred to as “dual stage” inflators. In practice, each such gas generant material-containing chamber is oftentimes referred to as a “combustion chamber” as the gas generant material therein contained is burned or otherwise reacted to produce or form gas such as may be used to inflate an associated inflatable restraint airbag cushion.
Dual stage inflators typically may have several contemplated actuation or firing scenarios. In a first such scenario, only the gas generant material in a first or primary chamber and associate initiator device is actuated whereby a fixed quantity of inflation gas is produced thereby. In a second possible scenario, the first or primary initiator is first actuated whereby gas generant material in a first chamber is first reacted to start to produce or form inflation gas and after a predetermined or preselected delay, a secondary initiator is then actuated whereby gas generant material in the second chamber is reacted to also produce or form inflation gas. In a third possible scenario, both the primary and the secondary initiators are actuated whereby a gas generant material in a first chamber and a gas generant material in a second chamber are actuated simultaneously to produce or form inflation gas from the gas generant material in each of the chambers.
Through the selection and use of an appropriate such actuation or firing scenario, inflator output parameters such as one or more of the quantity, supply, and rate of supply of inflation gas, for example, can be selectively and appropriately varied dependent on selected operating conditions such as one or more of ambient temperature, occupant presence, seat belt usage and rate of deceleration of the motor vehicle, for example.
Current state of the art automotive airbag technology oftentimes employs dual stage inflators (smart inflators) in an effort to achieve desired or necessary performance requirements.
FIG. 1 shows a n example of a dual stage inflator assembly, generally designated by the reference numeral 110, and shown in a static state or condition, e.g., prior to actuation.
The inflator assembly 110 includes a housing construction 112 having a generally cylindrical external outline and such as formed of two structural components, i.e., a lower shell or base portion 114 and an upper shell or diffuser cap portion 116. The diffuser cap portion 116 is in the general form of an inverted bowl and includes a top wall 120 and a cylindrical sidewall 122, which includes a plurality of spaced, preferably, generally uniformly spaced gas exit ports 124.
The base portion 114 includes first and second mounting openings, designated by the reference numerals 126 and 130, respectively. The base portion 114 also includes a peripheral bracket 132 that extends radially outward from the housing 112 and such as may serve to form an interface attachment which is used to attach the inflator assembly 110 to a vehicle.
The housing 112 is configured to define a central first chamber 134. The first chamber 134 contains or houses a supply of a first gas generant material, such as typically in the form of a pyrotechnic, not here shown to facilitate illustration and comprehension.
Within the first chamber 134, such as in surrounding relation with the first gas generant material therein contained, is a filter assembly 140. Such a filter assembly may include one or more of a combustion screen or filter such as formed of multiple layers or wraps of a metal screen, a filter damper pad or the like.
The inflator assembly 110 also includes a retainer 144 such as may serve as a construction expedient to retain the inflator assembly components in proper relative arrangement and prevent undesired flow passage through the assembly.
A first igniter assembly, generally designated by the reference numeral 154, is mounted to the housing 112 in a location within the first chamber 134 via the first mounting opening 126. The first igniter assembly 154 may take the form of a known pyrotechnic initiator device such as includes, as is known in the art, an igniter or ignition booster cup 156 wherein is housed a canister 158, such as contains an igniter material, not here shown to facilitate illustration and comprehension. The first igniter assembly also includes a first igniter device or squib 162 in conjunction with an initiator pyrotechnic output composition (not shown), a pyrotechnic output composition containment cup and electrical isolation sleeve 163, such as made of metal, and a squib adapter or holder 164 whereby the igniter assembly 154 is mounted to or mated with the housing 112. As shown, the igniter cup 156 can take the form of a generally concave member with a cap 170 and a cylindrical sidewall 172 forming an interior 174. The igniter cup 156 can be formed of a gas-impermeable material, such as metal, with the cylindrical sidewall 172 including a plurality of positioned and spaced gas exit orifices (not shown) that are normally (e.g., when the inflator is in a static or prior to actuation state) covered and the passage of material therethrough prevented by means of a pressure sensitive covering or barrier (not shown), such as by means of an adhesive-backed foil seal wrap or the like as is well known in the art. As is known, such covering can be selected to open or rupture upon the application of a predetermined pressure thereagainst from the interior of the igniter cup 156.
When actuated, the squib 162 discharges or otherwise results in the rupture or opening of the ignition material canister 158 and, in turn, ignition of the igniter material normally contained and subsequently the gas generant material contained within the first chamber 134.
In practice, the igniter assembly 154 is connected or joined to the housing 112 such as by welding the holder 164 to the base portion 114 at the mounting opening 126.
The first chamber 134 also houses or contains a second chamber 182. The second chamber 182 includes a generant cup 184, a lid closure 185, a second igniter device or squib 190 in conjunction with an initiator pyrotechnic output composition (not shown), a pyrotechnic output composition containment cup and electrical isolation sleeve 191, such as made of metal, and a second squib adapter or holder 192 whereby the second igniter device 190 and the associated second chamber 182 are mounted or mated with the housing 112 such as via the second mounting opening 130.
The generant cup 184 and the lid closure 185 cooperate to form a generant cup interior 196 wherein is desirably placed a selected quantity of a second gas generant material such as typically in the form of a pyrotechnic as described above and not here shown to facilitate illustration and comprehension. The second gas generant material may typically be in the form of a pyrotechnic material and may be either the same or different in composition, shape, size or form, as compared to the first gas generant material.
The generant cup 184 and the lid closure 185 further desirably cooperate and function in a manner such as to permit the combustion products formed by reaction of the gas generant material contained within the second chamber 182, when properly and desirably actuated, to pass from the second chamber 182 out into the first chamber 134, through the filter assembly 140 and the exit ports 124 out from the inflator assembly 110 and into an associated airbag cushion (not shown). Zone Name: A2,AMD
As will be appreciated, there is a need and demand for improvements in multiple initiator-containing devices and associated assemblies. Previous initiator and inflator devices include those described and/or claimed in EP 0 879 739 B1 (having the counterpart U.S. Pat. No. 6,068, 291, issued 30 May 2000 to Lebaudy et al.); EP 1 160 533 B1 (having the counterpart US 2002/0002924 A1, published 10 Jan. 2002); and U.S. Pat. No. 5,672,841, issued 30 Sep. 1997 to Monk et al.
In view of the numerous and/or varied uses and applications for initiators, improvements in the design, manufacture, operation and/or processing of initiators, such as whereby significant cost reductions can be realized, are highly sought, pursued and valued.